Several cases of excessive bleeding have been reported in people who take antibiotics. This side effect may be the result of reduced vitamin K activity and/or reduced vitamin K production by bacteria in the colon. One study showed that people who had taken broad-spectrum antibiotics had lower liver concentrations of vitamin K2 (menaquinone), though vitamin K1 (phylloquinone) levels remained normal. Several antibiotics appear to exert a strong effect on vitamin K activity, while others may not have any effect. Therefore, one should refer to a specific antibiotic for information on whether it interacts with vitamin K. Doctors of natural medicine sometimes recommend vitamin K supplementation to people taking antibiotics. Additional research is needed to determine whether the amount of vitamin K1 found in some multivitamins is sufficient to prevent antibiotic-induced bleeding. Moreover, most multivitamins do not contain vitamin K.

Reduce Side Effects

A common side effect of antibiotics is diarrhea, which may be caused by the elimination of beneficial bacteria normally found in the colon. Controlled studies have shown that taking probiotic microorganisms-such as Lactobacillus casei, Lactobacillus acidophilus, Bifidobacterium longum, or Saccharomyces boulardii-helps prevent antibiotic-induced diarrhea.

The diarrhea experienced by some people who take antibiotics also might be due to an overgrowth of the bacterium Clostridium difficile, which causes a disease known as pseudomembranous colitis. Controlled studies have shown that supplementation with harmless yeast-such as Saccharomyces boulardii or Saccharomyces cerevisiae (baker's or brewer's yeast)-helps prevent recurrence of this infection.

Treatment with antibiotics also commonly leads to an overgrowth of yeast (Candida albicans) in the vagina (candida vaginitis) and the intestines (sometimes referred to as "dysbiosis"). Controlled studies have shown that Lactobacillus acidophilus might prevent candida vaginitis.

Support Medicine

In one study, taking 500 mg of Saccharomyces boulardii twice daily enhanced the effectiveness of the antibiotic vancomycin in preventing recurrent clostridium infection. Therefore, people taking antibiotics who later develop diarrhea might benefit from supplementing with saccharomyces organisms.

Citrus Root Bark

The alkaloid citrusinine-1 from the root bark of citrus plants has been shown to enhance the antiviral activity of acyclovir. Further research is needed to determine whether taking citrus root bark would increase the effectiveness of acyclovir in humans.

Animal studies have shown that other herbs, including Geum japonicum, Rhus javanica, Syzygium aromaticum, and Terminalia chebula enhance the antiviral activity of acyclovir. Controlled human studies are needed to determine whether taking these herbs would increase the effectiveness of acyclovir in humans.

The flavonoids quercetin, quercitrin, and apigenin enhanced the antiviral activity of acyclovir in test tube studies. Controlled research is needed to determine whether taking quercetin or other flavonoid supplements would increase the effectiveness of acyclovir in humans.

Animal studies have shown that other herbs, including Geum japonicum, Rhus javanica, Syzygium aromaticum, and Terminalia chebula enhance the antiviral activity of acyclovir. Controlled human studies are needed to determine whether taking these herbs would increase the effectiveness of acyclovir in humans.

Animal studies have shown that other herbs, including Geum japonicum, Rhus javanica, Syzygium aromaticum, and Terminalia chebula enhance the antiviral activity of acyclovir. Controlled human studies are needed to determine whether taking these herbs would increase the effectiveness of acyclovir in humans.

Animal studies have shown that other herbs, including Geum japonicum, Rhus javanica, Syzygium aromaticum, and Terminalia chebula enhance the antiviral activity of acyclovir. Controlled human studies are needed to determine whether taking these herbs would increase the effectiveness of acyclovir in humans.

Test tube studies show that triptofordin C-2 increases the antiviral activity of acyclovir against the herpes virus. Controlled human research is needed to determine whether taking tripterygium would increase the effectiveness of acyclovir in humans.

Reduces Effectiveness

Khat

Khat (Catha edulis) is an herb found in East Africa and Yemen that has recently been imported into the United States. Studies have shown that chewing khat significantly reduces the absorption of ampicillin, which might reduce the effectiveness of the antibiotic. Therefore, people taking ampicillin should avoid herbal products that contain khat.

Potential Negative Interaction

none

Explanation Required

none

The Drug-Nutrient Interactions table may not include every possible interaction. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects. For details, refer to the manufacturers' package information as these are not covered in this table. If you take medications, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.

Please read the disclaimer about the limitations of the information provided here. Do NOT rely solely on the information in this article. The Healthnotes knowledgebase does not contain every possible interaction.

The information presented by Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over-the-counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2017.

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